1. Field of the Invention
This invention relates to a process for preparing a hydrogenating hydrocarbon resin.
2. Prior Art
Hydrocarbon resins have been used in adhesives and tackifiers as tackifying resins for providing the adhesive or tackifying properties to a variety of high polymers including rubbers such as natural rubber, SBR and chloroprene, ethylenic copolymers and waxes. Generally used tackifying resins are resins of natural origin, such as rosin and terpene resins, and a variety of petroleum resins. Amongst them, the rosin and terpene base resins have been widely used, since the former is excellent in adhesive and tackifying properties and is also soft at a low temperature and the latter is excellent in thermal stability. However, both of these resins are produced from natural resources, resulting in high cost of the products accompanied with a problem of restricted resources.
Although there has been proposed the use of relatively inexpensive petroleum resins in place of the tackifying resins of natural origin, a petroleum resin having the properties equivalent or superior to the rosin and terpene base resins has not yet been developed. In detail, the petroleum resins are generally produced by polymerizing fractions of cracked oil which are obtained by cracking of petroleum of the like. The fractions subjected to polymerization are those having boiling points distributing in wide ranges, for example, 20.degree. to 280.degree. C., 20.degree. to 140.degree. C. and 140.degree. to 280.degree. C. The resins obtained by using the fractions of cracked oil having boiling points ranging within about 20.degree. to 140.degree. C. are aliphatic hydrocarbon resins which do not contain aromatic rings. However, these resins are high in degree of unsaturation and inferior in hue and thermal stability, since the starting oil mixtures thereof contain large amounts of conjugated or non-conjugated diolefins. On the other hand, the resins obtained by polymerizing the fractions of cracked oil having boiling points ranging within about 140.degree. to 280.degree. C. are aromatic hydrocarbon resins. However, the resins of this type are unsatisfactory in thermal stability and hue and inferior in adhesive and tackifying properties when used for adhesive and tackifier applications.